Marine time domain CSEM: an emerging technology

For the past 40 years, the seismic method has been the geophysical workhorse of the oil industry. While it offers the best description of the reservoir shape and stratigraphy, it falls short on describing the fluid properties of the pore space as elastic waves predominantly travel through the rock matrix. In particular, many of the changes that take place during the production life of a reservoir do not exhibit a detectable acoustic property change. Marine controlled-source electromagnetic (CSEM) methods have found hydrocarbons after their response to thin resistors was understood (Eidesmo et al. 2002). With recent advances in electronics, time-domain, or transient CSEM data can now be reliably acquired in an offshore environment and make the leap from its dominant position in land EM to the marine world. We will discuss the recent developments in marine time-domain CSEM.